In a semiconductor manufacturing processing, e.g., a Ti film is formed on a bottom portion of a contact hole formed in a silicon wafer as an object to be processed; a TiSi is formed by an interdiffusion between Ti and Si of a substrate; a barrier layer such as a TiN or the like is formed on the TiSi; an Al layer, a W layer, a Cu layer and the like are formed on the barrier layer; and thus, holes are filled and wirings are fabricated. Conventionally, for performing a series of processings as described above, there has been employed a metal film forming system of, e.g., a cluster tool type having plural chambers. In such a metal film forming system, there is performed, prior to a film forming processing, a processing for removing a native oxide film, an etching damage layer and the like, which are formed on the silicon wafer, in order to obtain a fine contact. As for a device removing such a native oxide film, it has been known that an inductively coupled plasma is formed by using a hydrogen gas and an argon gas (Japanese Patent Laid-open Application No. H04-336426).
Further, as for a device performing a processing by forming an inductively coupled plasma, such a configuration has been known that a bell jar made of a dielectric material is provided at an upper portion of a chamber in which a semiconductor wafer as an object to be processed is disposed; and a coil inductor connected to an RF power supply is wound in an outer periphery of the bell jar to generate an inductively coupled plasma (Japanese Patent Laid-open Application No. H10-258227, H10-116826, H11-67746 and 2002-237486).
This kind of inductively coupled plasma processing apparatus, a portion of which is shown in FIG. 1, can be configured such that a plasma generation unit 400 including a bell jar 401, a coil 403, an RF power supply (not shown) and the like, is fixed to a chamber 201 accommodating therein an object to be processed by using a screw through a gas introducing ring 408 for introducing a processing gas.
To be specific, the bell jar 401 is fixed at the gas introducing ring 408 by using a screw component 410 by a bell jar clamping element 409. At this time, between the bell jar clamping element 409, the gas introducing ring 408 and the bell jar 401, there is inserted an annular buffer 409a made of a resin such as PTFE (polytetrafluoroethylene) or the like, to protect the bell jar 401.
The gas introducing ring 408 supporting the bell jar 401 is configured to be supported by a lid base 407, wherein the lid base 407 is mounted on the chamber 201.
Seal members 413 and 414 such as, e.g., O-ring or the like, are inserted into spaces formed between the bell jar 401 and the gas introducing ring 408, and between the lid base 407 and the chamber 201, to keep an airtightness therebetween.
For example, a processing gas such as an Ar gas, an H2 gas or the like is configured to be introduced into a processing space 402 from a gas channel 408b and a gas hole 408a communicating with the gas channel 408b. The processing gas introduced as mentioned above is plasma-excited to perform a plasma processing on a semiconductor wafer as a substrate to be processed.
In this case, scattered materials due to the plasma processing, e.g., a sputter etching, are adhered to a side of the gas introducing ring 408 or the lid base 407 to thereby become deposits. If the deposits are getting thicker, they are peeled off from a place where they have been adhered, to thereby become foreign materials. As a result, such problems as lowering in an operation rate of the device, lowering in a production yield of a semiconductor device and the like, are incurred.
For this reason, a cover shield 411 is configured to be attached by using a screw 412, to cover the gas introducing ring 408 and the lid base 407 inside the processing space 402. In case where the scattered materials due to the etching are adhered to the cover shield 411, the cover shield 411 is replaced by unscrewing and then tightly screwing back the screw 412, to thereby prevent foreign materials from being produced due to accumulation of deposits.
Further, a hole portion 411a having a diameter larger than that of a gas hole 408a is provided in the cover shield 411 in order not to block a diffusion of the processing gas introduced from the gas hole 408a. Accordingly, the deposits are likely to be adhered to the vicinity of the gas hole 408a of the gas introducing ring 408. Thus, the gas introducing ring 408 as well as the cover shield 411 needs to be replaced when performing a maintenance.
However, when replacing the cover shield 411, the bell jar 401, the gas introducing ring 408 and the lid base 407 need to be detached, thereby increasing the time for maintenance, which becomes problematic. Further, the gas introducing ring 408 has a complicated configuration wherein the gas channel 408b and the like are formed, and cost of a component to be replaced is expensive, thereby increasing the running-cost of the device and lowering a productivity of the semiconductor device.
Meanwhile, in such an inductively coupled plasma processing apparatus, a shape of the processing space applied for the plasma processing has not been studied in detail and the uniformity in the plasma processing is not necessarily satisfactory.
Further, as for a configuration of a susceptor mounting thereon a wafer inside a vessel, in which a plasma is generated, it has been widely known that an area for supporting the wafer is cut to have a recess portion to perform a positioning of the wafer (Japanese Patent Laid-open Application No. 2002-151412).
However, even in case of adopting such a configuration of the susceptor, the uniformity in the plasma processing is not satisfactory.